Is there a way to stop RealtimeDatabase's ValueEventListener from reading new data changes?-CodePudding

So ValueEventListener will keep changing the app's data whenever there is a change in RealtimeDatabase.

I want to create a button that stops the ValueEventListener from keeping updating the app with new data. How to do that? Thanks.

CodePudding user response：

So ValueEventListener will keep changing the app's data whenever there is a change in RealtimeDatabase.

Yes, that's correct. This is what a real-time listener does.

I want to create a button that stops the ValueEventListener from keeping updating the app with new data. How to do that?

In the same you have added the listener, you can remove it. So in code, it should look like this:

stopListenerButton.setOnClickListener {
    databaseReference.removeEventListener(valueEventListener);
}

There is another approach in which you don't actually need to remove the listener. If need that, you can use Query#addListenerForSingleValueEvent(@NonNull ValueEventListener listener):

Add a listener for a single change in the data at this location. This listener will be triggered once with the value of the data at the location.

Edit:

This is how you create a listener using an anonymous object:

val listener = object : ValueEventListener {
    override fun onDataChange(snapshot: DataSnapshot) {
        TODO("Not yet implemented")
    }

    override fun onCancelled(error: DatabaseError) {
        TODO("Not yet implemented") //Never ignore potential errors!
    }
}

This is how you attach the listener:

yourRef.addValueEventListener(listener)

And this is how you remove the listener:

yourRef.removeEventListener(listener)